This proposal is directed towards the elucidation of the morphological mechanisms involved in gastric mucus secretion produced as a response to the intake of water or saline solutions as well as various known secretagogues. By a combined approach using physiological parameters to measure released mucus and electron microscopy to observe its morphological correlate, the mechanisms of mucus secretion will be studied. The process exocytosis will be examined in detail and the possibility that holocrine and apocrine secretion may play a role in the sudden secretion of mucus will be examined. During and after extensive stimulation of mucus secretion, the biosynthesis of mucus will be traced by using tritiated hexoses and amino sugars as well as 35S incorporation which will be defected by autoradiography.